Generally, in a base station of a mobile communication, accuracy of time synchronization of several micro seconds or less is required. A time synchronization system, like GNSS (Global Navigation Satellite System), is therefore used. IEEE (The Institute of Electrical and Electronics Engineers) 1588 which defines the method for synchronizing a device on a network with accuracy of less than a micro second, can also be used for time synchronization.
PTL 1 discloses a technology on the time synchronization network and the communication apparatus which achieve time synchronization within required accuracy without increasing a network load or without increasing cost of mounting a highly accurate oscillator, when a base station which carries out time synchronization on the basis of GPS (Global Positioning System) and a base station which carries out time synchronization on the basis of GPS through a packet network using protocol, like IEEE 1588 exist in the same network.
PTL 2 discloses the technology related to the time synchronization system which synchronizes a time at a slave node to a time at a master node using protocol, like IEEE 1588.